Advances in optical imaging technologies have equipped researchers with extremely powerful tools to uniquely address clinically and biologically important questions that can only be accomplished in whole organ studies. Researchers equipped with these unique and ever improving tools can utilize optical microscopy and digital image analysis to study subcellular events within cells, cell-cell Interactions and integrative organ physiology, biochemistry, molecular and cellular biology. This has greatly enhanced the understanding of physiologic and disease processes, developmental biology, and has hastened and improved the reliability and interpretation of preclinical data. Multi-photon microscopy offers the investigator a minimally invasive high resolution technique with Increased depth of penetration and markedly reduced phototoxicity for visualization of cell-cell and intracellular events intravitally. A tremendous strength of the present O'Brien Center is our ability to customize our approach to individual user's needs. The Intravital Multi-photon Microscopy Core provides an extensive range of services including access to the necessary ICBM facilities and expertise in all aspects of intravital multiphoton imaging from utilization and training at the hands-on level to the theoretical aspects of microscopy, cell and molecular biology and kidney systems physiology.